Peavey Blazer 158 "Transtube" Guitar Amplifier REPAIR
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- Опубликовано: 9 сен 2024
- Picked this up for $20 almost completely dead (I say almost, as you'll see why in the video). It's kind of interesting to find a guitar amplifier NOT made in China. This one is actually made in Meridian Mississippi, USA (even though in the video I said I couldn't identify where it was made - even though it has printed Meridian MA on the back).
I believe "transtube technology" means they're using a discrete preamplifier design, which has distortion characteristics similar to valve state equipment.
If you have one of these Peavey amplifiers, or probably any Peavey amplifier that is dead, here's what you can do.
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I can appreciate a repair video that doesn't just take for granted the given advice to just "jumper the fuse". Nice troubleshooting even though it was a simple repair. Always a joy to watch my man!
Thanks. I wasn't sure including extra footage of me doing... really nothing, except making sure there wasn't a hidden nasty fault that caused the fuse to blow was a good idea. But, as I said, fuses don't blow for no reason. My thoughts; it's a class-ab amplifier, TDA2040, with a 1000uF output capacitor (I actually found the schematic for it!), so it should have internal short circuit protection. So, a short wouldn't have done it. This leads me to believe that the amplifier was just overloaded (probably repeatedly until the fuse weakened then blew). Another thing is, they're using a 3A fuse on a bridge rectifier comprising of 1N4004 diodes... it's only good for 1A! So why a 3A fuse?
@@AstrosElectronicsLab This is the kind of info a newbie/novice like me needs to hear. Thanks for the content, looking forward to the next video!
Thanks for this vid.
1/ "TransTube" looks to be Peavey TM marketing term indicating a solid state amp trying to reproduce traditional valve tube-like sound.
2/ Previewing other 158 repair vids (incl very similar "Rage 158" - no reverb device) would have quickly revealed dismantling process in the handle screws.
3/ Great work with installing the removable fuse option, and excellent tutorial of this.
4/ Your purchase visit to Jaycar would have been good opportunity to acquire and add on a 240V master power toggle at rear, prior to the transformer...??? (Though also likely something scavangable from a unrepairable 240V device.)
5/ Thanks also for demonstration of your troubleshooting the reason for the fuse blow.
6/ Two other 158 repair vids show that the much used phono socket for input is a failure point for poor design, and requiring resolderimg, given the four solder points are the only fixings for this socket. Other sockets would usually have much less usage. So whilst you were desoldering the fuse, would have been perfect opportunity to reflow those four points?
7/ One video also identifies from schematics that the thermal paste of the heat sink of the phones socket is also an issue area as it is also an earthing point - though perhaps only needed on possibly rare occasions when the phones socket is used - which then also auto-disables the signal taking volume to the speakers.
8/ This same repairer notes that the design of the handle screws holding in the chassis and going through the circuit-board, means that the whole weight of the amplifier is at times causing stress on the circuit board which would not be good for the solder points.
9/ Also whilst you had access, I'd wonder about servicing the pots (esp the most used volume, pre and post) and the channel push toggle with contact cleaner or alcohol? It sounded like the hum.waa mainly coming from the pre pot. My Rage 158, acquired yesterday on FB, has at least input socket issues, and I'm also wary or suspicious of these three pots and the channel push toggle. (I'm yet to open it up to start working on it.)
10/ Once again, great work and thanks heaps for this excellent video!
Thanks
Thanks for the very interesting and informative video. I got one of these (£19) but notice considerable mains hum. I was relieved to see at the end you do too, although you do have a lead plugged in. Tell me - does this one hum at idle (i.e., nothing plugged, clean channel, everything zeroed)? Mine does, almost tolerable but other amps I have are silent. But also with my 158 on turning up reverb the hum increases maybe 300%. Your reverb doesn't seem to have that effect.
Have same one. My transformer isnt putting out any voltage. We had a power surge and had 4 appliances with transformers go bad. Now have to find a replacement for this peavey
that fuse is called a pig tail fuse. no mains fuse bad design
yep